Yes I did found a solution.
What I did was to upload the files on a server first. Then at first session of the app, I downloaded that files to the local storage of the Expo app. Using filesystem api, then importing the index.html from assets solve the problem.
Tho, its so indirect and hard to maintain in terms of having to have a server or repository. So I used a github repository to store that data and download the files to local from there.
And actually published that app, see here: https://play.google.com/store/apps/details?id=org.dreamoriented.wordpack
You will notice that in the start of the game, it will sync files from remote github repository.
see filesystem api: https://docs.expo.io/versions/latest/sdk/filesystem.html
also downloadAsync method: https://docs.expo.io/versions/latest/sdk/filesystem.html#expofilesystemdownloadasyncuri-fileuri-options
I would really still love to have a way to do this in expo tho.
If you have any more questions mail me at firstname.lastname@example.org